Diagnostic Medical Sonography Program Vascular Technology Holdorf LECTURES 3 & 4 PART THREE Arterial Testing Signs, Symptoms, and Disease Mechanisms

Monophasic Slow upstroke Rounded peak Slow downstroke No reversal

Monophasic signal

Essential to observe for deterioration in the signals from one level to the next: as well as deterioration from a previous study A monophasic/dampened (pulsatile) signal is often obtained proximal to an obstruction. Well collateralized occlusions can appear similar to flow distal to a stenosis Vasodilation of the distal vessels often occur with proximal obstruction, reducing the pulsatility, causing the signals to have lower resistant (steady) flow quality.

Waveform Proximal to obstruction: Monophasic, pulsatile.

Waveform distal to obstruction: Monophasic, more steady

Suggestive of bilateral multi-level occlusive disease

Suggestive of Right Fem-Pop occlusive disease and some element of Aorto-iliac disease

Upper extremity Signals Subclavian Artery: High resistant, multiphasic flow. Proximal occlusion or critical stenosis will make the signal more monophasic Continuous signals can be found in the brachial, radial, and ulnar arteries in the relaxed and warm patient.

Doppler waveforms Post-exercise

Normal: Pre-exercise wave form qualities are maintained and or augmented. No reverse component.

Abnormal: Slow upstroke with more rounded peak, slow downstroke, no reverse component

Doppler waveforms Post-exercise continued. Absent Doppler signals may suggest occlusion or pre-occlusive vessel (string sign). Analog Doppler not capable of portraying velocities of less than 6 cm/sec

Interpretation-Quantitative (using spectral analysis) Pulsatility Index Acceleration Time

Pulsatility Index (PI) Calculated by dividing the Peak-to-Peak frequency difference (P1 – P2)by the mean average frequency.

Acceleration Time Based on the principle that proximal arterial obstruction results in a slowing of the time interval between the onset of systole to the point of maximum peak. Example: An acceleration time of > 133 msec suggests presence of proximal iliac disease.

NOTE: Both of these diagnostic techniques (Pulsatility Index and Acceleration Time) differentiate inflow from outflow disease. INFLOW represents the blood flowing into the lower extremities. Aorto-Iliac disease is an example of inflow disease. OUTFLOW represents the blood flow going out into the extremities: an example of which would be femoral-popliteal disease

Homework Chapters 3 and 4 of the workbook SDMS assignments Pages 43 - 68 SDMS assignments